It is well known in the art that high speed and high frequency signals three adjacent conductors interfere with each other and the signals degenerate. It is also well known in the art that when the conductors are shielded from each other, the interference is substantially reduced or even eliminated. Early examples of this is the well known coaxial cable and connectors that terminated such cable as shown in U.S. Pat. No. 4,070,751. As the use of two piece connector systems; e.g., the Eurocard connector, with printed circuit boards for high speed applications developed, the shielding concept was adopted by some workers as shown in U.S. Pat. No. 4,451,107 wherein the ground reference was provided by a die cast zinc housing. Other workers retained the dielectric housings for ease of manufacturing and cost and provided shielding by dedicating selected contact elements and posts. In U.S. Pat. No. 4,655,518, the patentees placed ground contacts along the outside of the rows of posts in the header and along the outside walls of the receptacle of their two piece connector system. This arrangement went a long way toward solving a "ground bounce" problem. More recently, workers have developed an even more powerful connector system wherein shielding plates are provided between adjacent rows of signal contacts. These arrangements; disclosed in U.S. Pat. No. 4,846,727 and application Ser. No. 07/367,929 filed June 19, 1989, permit the user to dedicate all contact elements and posts to carrying signals without a degradation thereof.
It is now proposed to provide coaxial contact elements for use in dielectric housings in which a signal carrying contact is surrounded by a ground reference contact.